busybox/miscutils/rx.c

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/* vi: set sw=4 ts=4: */
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/*-------------------------------------------------------------------------
* Filename: xmodem.c
* Version: $Id: rx.c,v 1.2 2004/03/15 08:28:46 andersen Exp $
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* Copyright: Copyright (C) 2001, Hewlett-Packard Company
* Author: Christopher Hoover <ch@hpl.hp.com>
* Description: xmodem functionality for uploading of kernels
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* and the like
* Created at: Thu Dec 20 01:58:08 PST 2001
*-----------------------------------------------------------------------*/
/*
* xmodem.c: xmodem functionality for uploading of kernels and
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* the like
*
* Copyright (C) 2001 Hewlett-Packard Laboratories
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*
* This was originally written for blob and then adapted for busybox.
*
*/
#include "busybox.h"
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#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <termios.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#define SOH 0x01
#define STX 0x02
#define EOT 0x04
#define ACK 0x06
#define NAK 0x15
#define BS 0x08
/*
Cf:
http://www.textfiles.com/apple/xmodem
http://www.phys.washington.edu/~belonis/xmodem/docxmodem.txt
http://www.phys.washington.edu/~belonis/xmodem/docymodem.txt
http://www.phys.washington.edu/~belonis/xmodem/modmprot.col
*/
#define TIMEOUT 1
#define TIMEOUT_LONG 10
#define MAXERRORS 10
static int read_byte(int fd, unsigned int timeout) {
char buf[1];
int n;
alarm(timeout);
n = read(fd, &buf, 1);
alarm(0);
if (n == 1)
return buf[0] & 0xff;
else
return -1;
}
static int receive(char *error_buf, size_t error_buf_size,
int ttyfd, int filefd)
{
char blockBuf[1024];
unsigned int errors = 0;
unsigned int wantBlockNo = 1;
unsigned int length = 0;
int docrc = 1;
char nak = 'C';
unsigned int timeout = TIMEOUT_LONG;
#define note_error(fmt,args...) \
snprintf(error_buf, error_buf_size, fmt,##args)
/* Flush pending input */
tcflush(ttyfd, TCIFLUSH);
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/* Ask for CRC; if we get errors, we will go with checksum */
write(ttyfd, &nak, 1);
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for (;;) {
int blockBegin;
int blockNo, blockNoOnesCompl;
int blockLength;
int cksum = 0;
int crcHi = 0;
int crcLo = 0;
blockBegin = read_byte(ttyfd, timeout);
if (blockBegin < 0)
goto timeout;
timeout = TIMEOUT;
nak = NAK;
switch (blockBegin) {
case SOH:
case STX:
break;
case EOT:
nak = ACK;
write(ttyfd, &nak, 1);
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goto done;
default:
goto error;
}
/* block no */
blockNo = read_byte(ttyfd, TIMEOUT);
if (blockNo < 0)
goto timeout;
/* block no one's compliment */
blockNoOnesCompl = read_byte(ttyfd, TIMEOUT);
if (blockNoOnesCompl < 0)
goto timeout;
if (blockNo != (255 - blockNoOnesCompl)) {
note_error("bad block ones compl");
goto error;
}
blockLength = (blockBegin == SOH) ? 128 : 1024;
{
int i;
for (i = 0; i < blockLength; i++) {
int cc = read_byte(ttyfd, TIMEOUT);
if (cc < 0)
goto timeout;
blockBuf[i] = cc;
}
}
if (docrc) {
crcHi = read_byte(ttyfd, TIMEOUT);
if (crcHi < 0)
goto timeout;
crcLo = read_byte(ttyfd, TIMEOUT);
if (crcLo < 0)
goto timeout;
} else {
cksum = read_byte(ttyfd, TIMEOUT);
if (cksum < 0)
goto timeout;
}
if (blockNo == ((wantBlockNo - 1) & 0xff)) {
/* a repeat of the last block is ok, just ignore it. */
/* this also ignores the initial block 0 which is */
/* meta data. */
goto next;
} else if (blockNo != (wantBlockNo & 0xff)) {
note_error("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
goto error;
}
if (docrc) {
int crc = 0;
int i, j;
int expectedCrcHi;
int expectedCrcLo;
for (i = 0; i < blockLength; i++) {
crc = crc ^ (int) blockBuf[i] << 8;
for (j = 0; j < 8; j++)
if (crc & 0x8000)
crc = crc << 1 ^ 0x1021;
else
crc = crc << 1;
}
expectedCrcHi = (crc >> 8) & 0xff;
expectedCrcLo = crc & 0xff;
if ((crcHi != expectedCrcHi) ||
(crcLo != expectedCrcLo)) {
note_error("crc error, expected 0x%02x 0x%02x, got 0x%02x 0x%02x", expectedCrcHi, expectedCrcLo, crcHi, crcLo);
goto error;
}
} else {
unsigned char expectedCksum = 0;
int i;
for (i = 0; i < blockLength; i++)
expectedCksum += blockBuf[i];
if (cksum != expectedCksum) {
note_error("checksum error, expected 0x%02x, got 0x%02x", expectedCksum, cksum);
goto error;
}
}
wantBlockNo++;
length += blockLength;
if (full_write(filefd, blockBuf, blockLength) < 0) {
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note_error("write to file failed: %m");
goto fatal;
}
next:
errors = 0;
nak = ACK;
write(ttyfd, &nak, 1);
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continue;
error:
timeout:
errors++;
if (errors == MAXERRORS) {
/* Abort */
// if using crc, try again w/o crc
if (nak == 'C') {
nak = NAK;
errors = 0;
docrc = 0;
goto timeout;
}
note_error("too many errors; giving up");
fatal:
/* 5 CAN followed by 5 BS */
write(ttyfd, "\030\030\030\030\030\010\010\010\010\010", 10);
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return -1;
}
/* Flush pending input */
tcflush(ttyfd, TCIFLUSH);
write(ttyfd, &nak, 1);
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}
done:
return length;
#undef note_error
}
static void sigalrm_handler(int ATTRIBUTE_UNUSED signum)
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{
}
int rx_main(int argc, char **argv)
{
char *fn;
int ttyfd, filefd;
struct termios tty, orig_tty;
struct sigaction act;
int n;
char error_buf[256];
if (argc != 2)
bb_show_usage();
fn = argv[1];
ttyfd = bb_xopen3(CURRENT_TTY, O_RDWR, 0);
filefd = bb_xopen3(fn, O_RDWR|O_CREAT|O_TRUNC, 0666);
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if (tcgetattr(ttyfd, &tty) < 0)
bb_error_msg_and_die("%s: tcgetattr failed: %m\n", argv[0]);
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orig_tty = tty;
cfmakeraw(&tty);
tcsetattr(ttyfd, TCSAFLUSH, &tty);
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memset(&act, 0, sizeof(act));
act.sa_handler = sigalrm_handler;
sigaction(SIGALRM, &act, 0);
n = receive(error_buf, sizeof(error_buf), ttyfd, filefd);
close(filefd);
tcsetattr(ttyfd, TCSAFLUSH, &orig_tty);
if (n < 0)
bb_error_msg_and_die("\n%s: receive failed:\n %s\n",
argv[0], error_buf);
bb_fflush_stdout_and_exit(EXIT_SUCCESS);
}